fixes #185, track const ctor dependencies, plus a static field fix

test/codegen/fieldtest.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fieldtest;
 
 class A {
   int x = 42;
 }
 
@@ skipping 33 matching lines @@
   int foo = 2;
   int bar = 3;
 }
 
 class Generic<T> {
   foo(T t) => print(bar + t);
 
   static String bar = 'hello';
 }
 
+class StaticFieldOrder1 {
+  static const a = b + 1;
+  static const c = d + 2;
+  static const b = c + 3;
+  static const d = 4;
+}
+class StaticFieldOrder2 {
+  static const a = StaticFieldOrder2.b + 1;
+  static const c = StaticFieldOrder2.d + 2;
+  static const b = StaticFieldOrder2.c + 3;
+  static const d = 4;
+}
+
 void main() {
   var a = new A();
   foo(a);
   bar(a);
   print(baz(a));
 
   print(new Generic<String>().foo(' world'));
 }